Pit-prop.



PATBNTBD FEB. 19, 190?.

P. MUMMBRTZ.

PIT PROP. APPLIUATIOH FILED APB.24.1906.

i391 fyi Fiyi Fl'fdya n2 .UNITED STATES PATENT OFFICE. PETER MoMMEi-ria; orY MARXEOH, GERMANY.

PIT-PROP.

Specification of Letters Patent.

Patented Feb. 19, 1907.

Application filed April 24, 1906. Serial No. 313.430.

To all whom, it may concern:

Be it known that I, PETER MOMMERTZ, a subject of the German Emperor, residing at Marxloh, Germany, have invented a new and useful Pit-Pro of which the following is a full and comp ete specification.

In the iron pit-props known at present, which are held to their required heights by cross-Wedges, binding-screws, te., there is the disadvantage that they either cannot be fixed at any required height or that the binding contrivance is so clumsy and inconvenient that it cannot be easily manipulated and that where great pressure is brought to bear on the prop it or the binding attachment gives Way. In the present invention these disadvantages are obviated by the prop being formed of two telescoping tubes, which 4are locked in position by a Wedge moving in the perpendicular or by a revolving eccentric. This locking is effected automatically. Hereby is attained not only a simple automatic locking arrangement, but the locking contn'va'nce in proportion to the increasing pressure put upon it effects a firmer locking of the tubes or Wedges, so that it is impossible for the tubes to telescope or to give way.

The prop is represented in the drawmgs in Figures 1 to 11, of which Fig. 1 is afront elevation; Fig. 2 a plan view in section, While Fig. 3 shows a mortised wedge and the prop in perpendicular section, in Fig. 4, crosssection, and 5 plan view in section, the employment of only one wedge being shown.

inally, Figs. 6, 7, and 8 represent a contrivance in which the laterally-adjustable Wedge or key carries another which is adjustable longitudinally. Figs. 9 and 10 make it clear that any form of fashioned iron may be used.

The pro is composed of a fixed lower member a, liaving foot c, and of an upperverticall movable member d, telescoped by mem er c. Upon' upper edge e of member a is supported a casing b, that rojects above said membervand is here provi ed with tapering key-seatsf. These key-seats are adapted for the reception of Wedges g, that also bear against the ower end of upper member d.

When the inner or upper part d of the prop i is inserted in the outer part a and ad'usted to position, the wedge gis inserted 1n the groove j' and the tube or fashioned iron is secured without further trouble, and a sli ing of same is rendered impossible. T e oosening, adjusting, &c., of the rop is very easily effected by giving a single Elow against the Wedge, which may be of an desired substance, Whereby part 'd is `berated. If, however, in the presence of great ressure it is desired to ease the prop, it can e readily effected, and with a little caution and attention there will be no breaking or bending of the prop, an evil which is ever present in those at present in use, as in thelr case the locking contrivance can only be reached with difficulty, and then the prop loses its portative power, whereas the present prop takes up its burden immediately. There may also be em loyed several similar telescoping tubes or fas 'cned-iron stays or girders also, there ma be some acking inserted betweenwedge an tube. 'lille stroke of the Wedge g may be limited by a binding-screw traversing through'the Wedge-lock or, as shown in Figs. 6 to'8, by a Wedge g', adjustable horizontally.

Having now fully described my invention, what I claim as new, and desire to secure by Letters Patent, is-

A pit-prop comlosed of a lower member, a casing supported t ereon and having a tapering key-seat above said member, an upper member teleseoped by the lower member, and a Wedge within the tapering key-seat that engages the upper member, 4substantially as specified.

Signed by me at Dsseldorf, Germany, this 29th day of March, 1906.

PETER MOMMERTZ. 

